ESTRO 2024 - Abstract Book

S2404

Clinical - Urology

ESTRO 2024

Azienda Ospedaliero-Universitaria, Bologna, Italy. 4 Nuclear Medicine, IRCSS Azienda Ospedaliera-Universitaria di Bologna, Bologna, Italy

Purpose/Objective:

68Ga-PSMA PET/CT is recognized as an effective restaging tool for patients with prostate cancer (PCa) undergoing salvage radiotherapy for biochemical relapse (BCR) after radical prostatectomy (RP). However, its sensitivity in patients with low PSA values (<0.5 ng/dL) remains a subject of debate. This analysis aims to present the 68Ga-PSMA PET/CT results in patients enrolled in an observational study of early salvage radiotherapy (esRT).

Material/Methods:

A total of 721 PCa patients were enrolled in the prospective EASY-1 trial after undergoing RP. Inclusion criteria were PCa treated with RP, including cases of pT2 with positive surgical margins (R1), pT3a regardless of surgical margin status or pT3b with negative surgical margins (R0), and a post-surgery PSA level undetectable 40 days after surgery (<0.01). Patients with nodal metastases were excluded. The surveillance protocol included regular PSA assessments over the years. EsRT was administered after a 68Ga-PSMA PET/CT scan in cases of BCR, defined as two consecutive PSA values ≥0.2 ng/ml.

Results:

As of now, 45 out of 60 patients referred for esRT have available 68Ga-PSMA PET/CT results. The findings are summarized in Table 1. The 68Ga-PSMA PET/CT scan identified gross disease in approximately one-third of cases (15/45). Specifically, the percentage of positive exams was 25.0% for patients with PSA <0.2 ng/dL and 38.5% for those with PSA ≥0.2 ng/dL (p=0.334). The site of PCa recurrence was the prostatic bed or nodal/bone metastasis in 40.0% and 60.0% of cases, respectively.

Conclusion:

This preliminary analysis suggests that 68Ga-PSMA PET/CT demonstrates sensitivity in detecting sites of macroscopic recurrence in patients undergoing esRT, even among those with low PSA levels (<0.2 ng/dL)